Category

Published on

25 Mar 2016

Abstract

NanoFET is a newly developed tool that simulates quantum mechanical size quantization in the inversion layer and phase coherent and ballistic transport properties in two-dimensional MOSFET devices. The overall simulation framework consists of the real-space effective mass non-equilibrium Green’s function equations solved self-consistently with Poisson’s equation. Solution of this set of equations is computationally intensive. Hence, nonuniform spatial grids are essential to limit the total number of grid points while at the same time resolving physical features. A novel algorithm for efficient computation of electron density without complete solution of the system of equations even in the presence of nonzero self-energies throughout the device has been used in this simulator[2]. The numerical problem consists in computing the diagonal elements of the matrix Gr = [ EI - H - ∑ ]-1 (retarded Green’s function) and G< = G∑<G† (electron correlation Green’s function), where E is the energy level, H is the device Hamiltonian matrix, and ∑ and ∑< are self energies († denotes the transpose conjugate of a matrix). The algorithmic flow is based on Dyson’s equation solved through recursive Green’s function approach. NanoFET has been parallelized with Message Passing Interface (MPI) and ported to various computing platforms at Purdue University. The MPI is applied in the integration procedure to calculate the charge density over the energy spectrum while the Green’s function at each energy point is calculated by a serial algorithm. The resulting speed-up factor shows a satisfactory scaling behavior for up to 32 processors. NanoFET has been benchmarked[3] against nanoMOS (a mode space approach to solving NEGF equations) and QuaMC (Quantum-corrected Monte-Carlo) simulators that are available on nanoHUB.org.

Credits

NanoFET has been parallelized with MPI and ported to various platforms at Purdue University, West Lafayette, IN, USA. More information on NanoFET can be found by contacting Shaikh S. Ahmed.